A randomized trial tested whether giving a 10-mL/kg IV crystalloid bolus before pericardiocentesis in dogs with pericardial effusion actually improves cardiovascular parameters. It didn't, shock index dropped after the tap in both groups, but the fluid bolus made no difference.
What the study found
Thirty dogs with pericardial effusion were randomized to receive either a 10-mL/kg IV bolus of compound sodium lactate over 10 minutes before pericardiocentesis or no fluid bolus. Shock index (heart rate divided by systolic blood pressure) decreased significantly after pericardiocentesis in both groups, but there was no difference in shock index between the groups at any time point. The fluid bolus did not produce adverse respiratory effects, no dogs required supplemental oxygen by four hours post-tap, and respiratory rate did not differ between groups. The no-fluid group had a higher incidence of new B-lines on point-of-care ultrasound (60% versus 20%), but the median B-line score remained ≤1 at all sites at baseline and at four hours. Twenty-four of thirty dogs survived to hospital discharge with no difference in survival between groups.
How the study was built
This was a prospective, randomized, nonblinded clinical trial conducted at a single university teaching hospital from January 2021 to November 2022. Thirty dogs diagnosed with pericardial effusion were enrolled. Cardiovascular parameters, respiratory rate, peripheral blood lactate, and point-of-care ultrasound findings were assessed at four time points: baseline, 15 minutes later (after fluid bolus for the treatment group), immediately after pericardiocentesis, and four hours after pericardiocentesis. The trial was not blinded, clinicians knew which dogs received the bolus. A single-center design and a small sample limit how broadly the findings apply, and the authors state the study was underpowered to detect a significant difference.
The number, and its error bars
Significant decreases in shock index were observed in the no-fluid group between the 15-minute mark and immediately post-tap (p = 0.034) and between the 15-minute mark and four hours post-tap (p = 0.003). In the fluid-bolus group, shock index decreased significantly only between the 15-minute mark and four hours post-tap (p = 0.027). No differences in shock index were found between the groups when compared at the same time point. The incidence of new B-lines was 60% in the no-fluid group versus 20% in the fluid-bolus group, but the median B-line score was ≤1 at all ultrasound sites at baseline and at four hours.
What the authors say it cannot tell you
The authors state the study was underpowered to detect a significant difference and that further studies are needed. The trial was conducted at a single university teaching hospital, which limits generalizability. The study was not blinded, so clinician behavior and assessment could have been influenced by knowledge of group assignment. The abstract does not state other limitations the authors may have discussed.
Who paid for it
The abstract does not state who funded the study or what conflicts of interest were declared.
What this means for your practice
VeterinaryPracticeNow's read, not the study's. Everything in this section is our editorial interpretation for practice owners. The study does not claim any of it.
If you've been giving a crystalloid bolus before every pericardiocentesis because it felt like the right move, this trial found no difference in shock index between dogs that got the bolus and dogs that didn't. The tap itself is what dropped shock index in both groups. That matters for the associate managing the case alone in the middle of the night, one fewer thing to set up, one fewer bag to hang, and no delay if the dog is crashing and you need to tap now.
The respiratory safety finding is useful for the owner-DVM deciding whether to stock this protocol: the bolus at this dose did not require oxygen support or drive respiratory rate up, even though more dogs in the no-fluid group showed new B-lines. The B-line scores stayed low, which suggests the fluid was tolerated even when it showed up on ultrasound. If you're going to give the bolus anyway, because the dog is also hypovolemic, or because you want the venous access secured, this trial says it appears safe at this dose, just not beneficial for the effusion itself.
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The bigger operational question: does this change your tamponade protocol, or does the small sample and the single-center design leave you waiting for the next trial? Thirty dogs is a real number for a condition this acute, but the authors themselves say the study was underpowered. The trial gives you data on what happened when the bolus was given and when it wasn't, and it found no difference in the outcome that was measured.